4O SOILS 



When humus is present in the soil in any appreciable 

 quantity, it increases the ease of flow at least, its ab- 

 sorption for the clay types. In this respect it is manifest 

 that humus is a valuable contribution to both these soil 

 types. Without humus, both sand and clay are at a dis- 

 advantage, each showing the loss not only at harvest- 

 time but throughout the growing periods, regardless of 

 crop, or season, or section. 



Three forms in which water exists in the soil. Three 

 kinds of water are present in soils : gravitational water 

 capillary water, and hygroscopic water. 



Immediately after a rain, gravitational water, or that 

 which will move under the influence of gravity, is present 

 in the soil, where it remains until it works its way down- 

 ward into the subsoil or until it is removed by nat- 



'A-- ' V.- 'i V'\- ' .Vtot^fc-- 1 A, 



CIRCULATION OF WATER IN THE SOIL 



By gravity water KOCS into the soil, by capillarity it circulates through the 



so'il and upwards, and unless prevented by a mulch, it goes 



out into the air by evaporation 



